Jean-Francois Lyotard is one of the best-known post-modernists of the day, and the book of The Post-modern Condition is his most famous writing. Taking the legitimacy of science as the theme of the book, Lyotard has criticisms of foundationalist, universalist and essentialist conceptions of science. He makes a profound analysis of "speculative narratives, " "liberation narratives" and "technical narratives" in modern science and puts forward his own post-modernist conception of science.